19 replies to this topic

[nicolae1]

Does anybody use 9Jx17 rims to the rear with T45 wishbones and Gt Race uprights ? ( the ones from elise parts )

I have tried to use some rims called Motec but I have this problem :



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The front part of the lower rear wishbone touches the rim
I wonder if I could get rid of this problem with ATS DTC reems or GTR Rial rims
The ET of my rims is 30
I think if my rims would have an ET of 20 mm there will be no problem anymore
Does anybody know which are the trade-offs in using an smaller ET than the 35 mm one recommender by the producer ?

Here are some links to the wishbones and uprights that I have

http://picasaweb.goo...tsAndWishbones#

[siztenboots]

I think chris randall is probably the only one likely to be running the EP wishbone setup and have experience with 17/18 9J wheels on his race europa

[cnrandall]

I'm on nitron uprights (which are lovely!) with stock wishbones (all rose jointed). Best bet is to give Geary a call I imagine.

[nicolae1]

I'm on nitron uprights (which are lovely!) with stock wishbones (all rose jointed). Best bet is to give Geary a call I imagine.

I did.
He told me that the maximum width they use on Lotus is 8".
I thought that maybe somebody else used a 9 inch rim.

Anyway could you tell me : a rim with an ET lower than the rocommended one ( 35 mm afaik ) is a proper rim for racing this car.
I know that for a FWD car is not a good thing to use other offset than the recommended one because this thing induce some drag in stright line acceleration .
I do not now for a RWD car.
I think that a lower offset will transfer less weight on the wheel , which is not a bad thing ( more understeer instead of oversteer )
Is there everything else I should now regarding this matter. ( lower ET rims to the rear )

Edited by nicolae1, 01 December 2010 - 05:53 PM.

[Nev]

I can't help you Nicolae, but keep going. Your project is inspiring and I still hope to meet you (and the car) someday

[JimmyJamJerusalem]

Can't you space them out a little? Flare the wheel arch, lovely!!

[nicolae1]

Can't you space them out a little? Flare the wheel arch, lovely!!

This means using a rim with an ET lower than 30 . Et 10 or 20 would give me the clearance that I need.
But , isn't any trade-off in using this lower ET , much lower than the one recommended by the producer.

[siztenboots]

Can't you space them out a little? Flare the wheel arch, lovely!!

This means using a rim with an ET lower than 30 . Et 10 or 20 would give me the clearance that I need.
But , isn't any trade-off in using this lower ET , much lower than the one recommended by the producer.

by moving the wheel outwards , you increase the lever length of the rotating mass , and thus the force the suspension has to control, your effective spring rate becomes less.

by moving the non steering wheel outwards you increase the wheel track and alter the dynamic transitions roll etc.

if you put another clamping surface between the bolt-wheel-spacer-hub , then you now have three "-"'s for the bolt to clamp which isn't so good, ideally the spacer would be hub centric and have stubs, so you clamp the spacer to the hub, then attach wheels to the spacer.

[nicolae1]

by moving the non steering wheel outwards you increase the wheel track and alter the dynamic transitions roll etc.

if you put another clamping surface between the bolt-wheel-spacer-hub , then you now have three "-"'s for the bolt to clamp which isn't so good, ideally the spacer would be hub centric and have stubs, so you clamp the spacer to the hub, then attach wheels to the spacer.

I do not intend to put a flange between the rim and the hub.
I want to buy other rims with an ET lower than the one I have now.

My present rear spring rate is 600 or 650 I am not sure right now.I suppose it can cope with the new position of the wheel ; what do you think ?


Does the distance between where the imginary point going from the telescope touch the ground and the point from the midlle of the tire touch the ground have any implication in case of a RWD car ?

I will look over " dynamic transition roll ' to see what this means.

[Dominique]

I do not intend to put a flange between the rim and the hub.
I want to buy other rims with an ET lower than the one I have now.

If your looking for rims with different offset, skip the DTC's. They have also the 30mm.

I've compared some of your pics with the one below (nicked out of an other topic), your new uprights seems quite a lot higher.




I hate to say it, but you probably will need 18" rims.

[nicolae1]

I hate to say it, but you probably will need 18" rims.

First option is to find a 17" rim.
This way the tyres that I have are not a complete waste of money.

I refered to ATS DTC only because I thought that there are people that use my configuration ( uprights , wishbones ) with that kind of rims. I thought that maybe the inside lip of an ATS DTC rim has such a shape that allow it to revolve without touching the wishbone ( even if it has the same ET as my rim ).

I found a Team Dynamics rim 9Jx17 ET 23 but I am not sure if that is enough. ( and I do not know if their hub center hole is suitable for my car ; 61,5 )

[siztenboots]

standard centre bore to fit the hub is 65.1mm some of us run an oversized bore with a small centering attachment ring td pr 1.2 offsets taken from rimstock 8.0 x 17 e20 / 25 / 33 / 38 / 40 / 48 / 53 9.0 x 17 e23 / 27 / 30 / 35 / 40 / 45

[Exmantaa]

ATS DTC's 9x17 are also available in several ET's. But anything lower than ET30 (27) will need wheel arch extensions.... (I would do some trial fitting with spacer plates first before ordering some new wheels)

[Speedy4Fun]

You can buy the ATS DTS 9x17 wheels in any offset between -10 and +50 on request. However going lower then ET30 will make your wheels stick out of the arches with 'normal' camber settings (-2,2) I have ATS DTC 9x17 with ET27 and camber -2,2 and they stick out slightly. If you have more camber they will stick out less/not. Don't know if your camber setting is set as you want it, but more camber would give more clearance. Try to space out the wheel a few mm's, maybe in combination with more camber to figure out what offset will work. Then you can order the ATS wheels with the proper offset. (didn't see Exmantaa comment, basicly the same, but changing camber can also help)

Edited by Speedy4Fun, 03 December 2010 - 03:57 PM.

[Exmantaa]

Camber setting will not you help much at the point where it rubs here on the lower wishbones... Space wheels out, modify wishbones where they rub or change back to OEM uprights... ( )

[nicolae1]

camber setting that I use is -2,5 wheel arch extension is next on the list I am glad to hear that ATS has many offset choices. I will probably solve this matter easier than I thought.

[Crabash]

Havent got a good pic of my DTC's and I have standard wishbones. but this is what I have it if helps.

[Arno]

I've compared some of your pics with the one below (nicked out of an other topic), your new uprights seems quite a lot higher.

That is the point of Nitron or for instance Eliseparts GT uprights. The axle center is moved up about 20mm on each of these uprights.

This means that the car is immediately 'lowered' by 20mm (even without touching the suspension), but keeps the correct wishbone geometry for longer if you lower it further than that with different suspension on it.

If you lower a car to 100mm or less on the normal uprights then the wishbones start to angle upwards at it's base setting and this is not good for the road holding as it messes up a number of things (eg. you're way off on the bumpsteer graph, your dampers run out of compression stroke, the camber gain is wrong, etc.).

By moving the axle line up on the uprights you move the wishbones down and back to horizontal, so the suspension can 'work' properly again.

Disadvantage (as shown on this thread) is indeed that your lower wishbones get closer to the wheel edge, so to stop super-wide wheels from rubbing you'll need to lower the wheel offset and perhaps modify the clam with arch extentions to keep the tyre covered.

In thid case with a 9J wheel and corresponding tyre (245? 255?) I'd be surprised if it didn't rub on the inside of the arch liners too with the normal affset, so it needs to move outward anyway...

Bye, Arno.

[siztenboots]

adjusting camber might be all you need 17" = 431.8mm 1 degree of extra camber @ 216mm = 1.8mm extra clearance to wishbone, same offset , but less clearance at top of wheel to chassis / other bits if you spaced the wheel out 5mm extra offset, to return the top of the wheel to its same position relative to the clam, you are going to need more negative camber, ie. 5/1.8mm degrees

[nicolae1]

adjusting camber might be all you need

If you ask me , -2.5 degree is quite a lot ( with a 650lb rear spring rate )
I would like to keep it this way and obtain a margin from the wheel offset ( this margin should allow me the toe in that I want ; 2,5mm ( more or less )
I am allmost sure that I will have to modify the arches of the clam in order to suit ; but I assumed this when I chose 255 tyres.

There is hope . From the picture above ( ATS DTC ) The inside lip have such a shape that ( assuming it is the same shape on the inner part of the rim , too ; the part we cannot see it in the picture )it could allow me to run such a rim even with a 30 mm ET . I have to have a closer look to such a rim . It could be an easy fit.